1. Field of the Invention
The present invention relates to a date identification apparatus.
2. Description of the Related Art
Apparatuses are known that identify (or recognize) characters on paper or other medium on the basis of an image captured of the medium. Such an identification apparatus performs various types of image processing for the captured image to thereby enhance identification performance. For example, one known identification apparatus uses saturation or luminance of pixels in the image to classify each pixel within the image into a background, a character, and other elements, thereby allowing the character or the like to be identified (e.g., Japanese Patent Application Laid-open No. 2013-84071). Another known identification apparatus calculates a frequency histogram of luminance in the image, thereby binarizing the image on the basis of a binarization threshold so as to achieve a predetermined black ratio value (e.g., Japanese Patent Application Laid-open No. 08-221512).
Still another known identification apparatus uses a unique technique for identifying characters. Assume, for example, the character to be identified has a segment structure. The known identification apparatus has a dictionary memory prepared in advance for each character. The dictionary memory stores therein used segments and unused segments for each character. The known apparatus determines a character on the basis of the dictionary memory and data isolated from positions in the captured image corresponding to the segments (e.g., Japanese Patent Application Laid-open No. 2000-339472).
An extremely large amount of calculations is, however, involved in performing image processing to thereby sift through pixels that are likely to constitute a character and to determine whether these pixels are combined together to form a character. Additionally, in identifying a character having the segment structure and in determining whether each pixel in the image is one that constitutes a segment, a large amount of calculations is again involved in making an appropriate determination that can be difficult depending on the condition of the captured image.
One example of identifying a character in an image may be found in a case in which old photos are digitized for saving. The attempt to digitize the old photos may include, in order to sort the photos in chronological order, a step of identifying a date assigned to each photo as a result of the date being printed thereon. Specifically, in order to sort digitized data by the date, the date assigned to each photo is identified and the digitized data are sorted according to the identified date. Thus, when the digitized photos are sorted by the date, the identification apparatus is employed to identify the date assigned to each photo. If the photo is old, however, the date may be indistinct as a result of deterioration and the degree of deterioration may vary from one photo to another. In such a case, isolating pixels that constitute the date assigned to the photo is an extremely difficult task. This increases the amount of calculations required for the identification even further. Thus, the identification of the date is an extremely difficult task.